In recent years, data such as images and video is increasingly transferred via a network such as an IP network. For example, an ASP (Active Server Pages) system that operates a server screen from a client at a remote location via a network transfers image data via the network.
When data is transferred via a network, related technologies such as data compression, data encoding, data decoding, and retransmission are generally used. These related technologies are disclosed, for example, in Japanese Unexamined Patent Application Nos. 10-285205, 2007-274309, 10-65675, and 11-17737.